The Wedge ROP is a render output driver, which can be used to change variables on the fly while rendering. This can be very useful when simulating, in that you can test out different parameters to see the different results. It's a relatively new feature in Houdini 9.5.
Wedging will render a specified ROP multiple times, each time varying some parameters in the .hip file. This is useful for exploring how changing parameters will change the final product of things such as simulations.
***HOUDINI APPRENTICE USERS:
Due to the way that Apprentice automatically saves images in a non-commercial format, you may encounter difficulty if you try to save your images as ".pic" at the end of this lesson. Please make sure that on your Mantra Output Driver, that you save your Output Picture as ".picnc" rather than ".pic" when attempting to use Post Frame Scripts. Attempting to render as ".pic" will cause the Post Frame Script to fail.
Download the Scene Files for this project.